/**
 * Turns the `banner` option into the header prepended to each generated file.
 *
 * A message is wrapped in a JSDoc block, which reads well and is what most
 * headers want. Text made only of `//` lines is emitted as written,
 * because some headers are directives rather than prose, and only the
 * line-comment form counts as one: TypeScript ignores a `@ts-nocheck` inside
 * a block comment, so `--banner "// @ts-nocheck"` was the one header a strict
 * project needed and the one the wrapping made impossible.
 */
export declare const resolveBanner: (banner: boolean | string | undefined) => string;